Validating data in wpf

object, any fields in the affected field layout will automatically report data errors.

You can selectively disable this feature on a field by setting the Support Data Error Info property exposed by a field object’s Field Settings property to interface and you set the Value Constraint property of an embedded xam Editor control, any value constraint errors will also cause the error icon and/or highlight to appear.

validating data in wpf-5

When validation fails, the error message to display is `Last name is required.´”. Raising the Property Changed event is very important to ensure that binding works and for the framework to know when a property has changed.

Since we’re using some Text Box controls it might be worth mentioning that Text Box.

field A should only be validated if field B is true) using nothing but attributes (and of course a little bit of helper code, which I’ll give you). Before you get started, you need to add a reference to the System. To change the mode, you can set the property `Use Explicit Validation´ in your view-model constructor (or change it at any time elsewhere).

The idea behind this is to be able to do something like this: Looking at the [Required If(...)] attribute, simply put it means: “`Last Name´ is required if the property `Is Last Name Required´ equals true. Okay, let’s have a look at our view-model and the XAML for the window we will be binding to the view-model: Main Window View Note that in the constructor I am setting `Use Explicit Validation´ to true, and also that I am raising the `On Property Changed´ event each time a property is set.

If the property’s value exists in Values, then the `value´ parameter in our Is Valid() implementation is subjected to validation.

Anyways, in an effort to stop making this post longer and longer I’m going to stop explaining at this point and give you the download link to the sample project. If there’s anything that you don’t understand, don’t hesitate to post a comment or e-mail me and I’ll try to explain further.

The combination of these two is what makes it possible to be aware of the view-model instance which is being validated, coincidentally providing us access to all of its properties as well.

Almost all of the attribute validation examples that I have seen thus far make use of the Validation Attribute.

Value constraints will force your end users to correct an error before they can move focus to a new cell.

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